Most modern automotive fuel systems utilize fuel injectors to provide precise metering of fuel for introduction into each combustion chamber. Additionally, the fuel injector atomizes the fuel during injection, breaking the fuel into a large number of very small particles, increasing the surface area of the fuel being injected, and allowing the oxidizer, typically ambient air, to more thoroughly mix with the fuel prior to combustion. The metering and atomization of the fuel reduces combustion emissions and increases the fuel efficiency of the engine. Thus, as a general rule, the greater the precision in metering and targeting of the fuel and the greater the atomization of the fuel, the lower the emissions with greater fuel efficiency.
An electro-magnetic fuel injector typically utilizes a solenoid assembly to supply an actuating force to a fuel metering assembly. Typically, the fuel metering assembly is a plunger-style needle valve which reciprocates between a closed position, where the needle is seated in a seat to prevent fuel from escaping through a metering orifice into the combustion chamber, and an open position, where the needle is lifted from the seat, allowing fuel to discharge through the metering orifice for introduction into the combustion chamber.
The fuel injector is typically mounted upstream of the intake valve in the intake manifold or proximate a cylinder head. As the intake valve opens on an intake port of the cylinder, fuel is sprayed towards the intake port. In one situation, it may be desirable to target the fuel spray at the intake valve head or stem while in another situation, it may be desirable to target the fuel spray at the intake port instead of at the intake valve. In both situations, the targeting of the fuel spray can be affected by the spray or cone pattern. Where the cone pattern has a large divergent cone shape, the fuel sprayed may impact on a surface of the intake port rather than towards its intended target. Conversely, where the cone pattern has a narrow divergence, the fuel may not atomize and may even recombine into a liquid stream. In either case, incomplete combustion may result, leading to an increase in undesirable exhaust emissions.
Complicating the requirements for targeting and spray pattern is cylinder head configuration, intake geometry and intake port specific to each engine""s design. As a result, a fuel injector designed for a specified cone pattern and targeting of the fuel spray may work extremely well in one type of engine configuration but may present emissions and driveability issues upon installation in a different type of engine configuration. Additionally, as more and more vehicles are produced using various configurations of engines (for example: inline-4, inline-6, V-6, V-8, V-12, W-8 etc.,), emission standards have become stricter, leading to tighter metering, spray targeting and spray or cone pattern requirements of the fuel injector for each engine configuration.
It would be beneficial to develop a fuel injector in which increased atomization and precise targeting can be changed so as to meet a particular fuel targeting and cone pattern from one type of engine configuration to another type.
It would also be beneficial to develop a fuel injector in which non-angled metering orifices can be used in controlling atomization, spray targeting and spray distribution of fuel.
The present invention provides fuel targeting and fuel spray distribution with non-angled metering orifices. In a preferred embodiment, a fuel injector is provided. The fuel injector comprises a housing, a seat, a metering disc and a closure member. The housing has an inlet, an outlet and a longitudinal axis extending therethrough. The seat is disposed proximate the outlet. The seat includes a sealing surface, an orifice, and a first channel surface. The metering disc includes a second channel surface confronting the first channel surface. The closure member is reciprocally located within the housing along the longitudinal axis between a first position wherein the closure member is displaced from the seat, allowing fuel flow past the closure member, and a second position wherein the closure member is biased against the seat, precluding fuel flow past the closure member. The metering disc has a plurality of metering orifices extending therethrough along the longitudinal axis. The metering orifices are located about the longitudinal axis and define a first virtual circle greater than a second virtual circle defined by a projection of the sealing surface onto a metering disc so that all of the metering orifices are disposed outside the second virtual circle. The projection of the sealing surface converges at a virtual apex disposed within the metering disc. A controlled velocity channel is formed between the first and second channel surfaces, the controlled velocity channel having a first portion changing in cross-sectional area as the channel extends outwardly from the orifice of the seat to a location cincturing the plurality of metering orifices, such that a flow path exiting through each of the metering orifices forms a spray angle oblique to the longitudinal axis.
In another preferred embodiment, a seat subassembly is provided. The seat subassembly includes a seat, a metering disc contiguous to the seat, and a longitudinal axis extending therethrough. The seat includes a sealing surface, an orifice, and a first channel surface. The metering disc includes a second channel surface confronting the first channel surface. The metering disc has a plurality of metering orifices extending therethrough along the longitudinal axis. The metering orifices are located about the longitudinal axis and define a first virtual circle greater than a second virtual circle defined by a projection of the sealing surface onto a metering disc so that all of the metering orifices are disposed outside the second virtual circle. The projection of the sealing surface converges at a virtual apex disposed within the metering disc. A controlled velocity channel is formed between the first and second channel surfaces, the controlled velocity channel having a first portion changing in cross-sectional area as the channel extends outwardly from the orifice of the seat to a location cincturing the plurality of metering orifices, such that a flow path exiting through each of the metering orifices forms a spray angle oblique to the longitudinal axis.
In yet another embodiment, a method of controlling a spray angle of fuel flow through at least one metering orifice of a fuel injector is provided. The fuel injector has an inlet and an outlet and a passage extending along a longitudinal axis therethrough. The outlet has a seat and a metering disc. The seat has a seat orifice and a first channel surface extending obliquely to the longitudinal axis. The metering disc includes a second channel surface confronting the first channel surface so as to provide a frustoconical flow channel. The metering disc has a plurality of metering orifices extending therethrough along the longitudinal axis and located about the longitudinal axis. The method is achieved, in part, by locating the metering orifices on a first virtual circle outside of a second virtual circle formed by an extension of a sealing surface of the seat such that the metering orifices extend generally parallel to the longitudinal axis; and imparting a radial velocity to the fuel flowing from the seat orifice through the controlled flow channel, so that a flow path through each of the metering orifices forms a spray angle oblique to the longitudinal axis.